I remember this as if it was yesterday…
I was in 9th grade gym class, running laps around the track. Right when I was entering the bend, near the end zone - a certain Coach Weatherwax, standing on the opposite 40 yard line, let rip the loudest fart I have heard in all my 25 years.
Now after I heard it, and looked back to see the proud grin on Coach Weatherwax, I started to catch wind of something.
I estimated that the fart had a tremendous volume, equal to the gaseous content of a Chico’s Tacos 3.99 special with what had to be a Dr. Pepper - straw ingested of course.
He was approximately 60 yards away. If the speed of sound is roughly 335 meters a second…that meant that the fart was let a little over 1/5 of a second before the smell hit.
It took approximately 3.5 seconds for me to think " Whoa!.. I hope I’m not downwind from…SHIT!". So I estimate that the fart’s smell traveled the 60 yards in 3.75 seconds.
Where I got stuck was where I tried to make a slope of the exponential decay - I figured the initial velocity was probably several times greater - and at 120 yards or so, it would have dissipated into the general scent.
Also, since this was in a football field the metal bleachers would have created a fart echo - perhaps a fartdoppler effect - reverberating the fart in undulating waves.
Also there may have been secondary interference. Speaking from experience, if someone lets a really loud one, others seize the opportunity and squeeze off some of their gas with relative impunity. With 10 or 12 other guys along the track that morning, there may have been a compound fart effect (observe dissert. of M. Brooks on that subject, from 1973)
An finally, pant thickness is a major factor.
As a result, any accurate fart speed measurement must involve a naked subject in an insulated seal level tunnel, with precise calibrating equipment. Any volunteers?